The present invention has utility in applications requiring the conversion of an analog signal into a digital signal, for example for computer sensing of analog information in an automotive control system. To further illustrate, in an automotive engine control system, a microcomputer requires analog signal information from various transducers to be converted into digital signal information before it can be processed by the microcomputer. Examples of such analog signal information are the outputs of sensors for manifold pressure, oxygen, rotational speed, operator input, battery voltage, anti-knock, etc.
In a typical automotive application, many different analog signals need to be converted. Typically the software in a host central processing unit (CPU) would specify which analog channels needed to be sampled, when they were to be sampled, and how they were to be sampled. However, the prior art A/D conversion systems had the disadvantage of burdening the host system software with starting each conversion and then waiting for the conversion to complete.
Thus there is a significant need to provide an A/D converter system in which the host system software is freed from the responsibility of initiating sampling, conversion, and storing results from an A/D converter.